A pneumatic rubber tire is conventionally of a toroidal shape and comprised of a carcass with a cavity in which its closure is typically completed with a rigid rim onto which the tire is to be mounted. Such pneumatic tire and pneumatic tire/rim assembly is well known.
The inner surface of a pneumatic tire, namely a surface of said cavity which is sometimes referred to as an “innerliner” is typically a rubber layer composed of an elastomeric composition designed to prevent, or retard, the permeation of air and moisture into the tire carcass from the aforesaid cavity which becomes the tire's inner air chamber. Such tire innerliners, or innerliner rubber layers, are well known to those having skill in such art.
Butyl rubber is typically relatively impermeable to air and moisture and is often used as a major portion of the tire innerliner composition and can be in a form of butyl rubber or halobutyl rubber such as, for example, bromobutyl rubber. For example, see U.S. Pat. No. 3,808,177. Butyl rubber is an isobutylene copolymer with a small amount of isoprene which typically contains only from about 0.5 to about 5 weight percent units derived from isoprene.
Halobutyl and butyl rubbers are usually one of the most expensive elastomers used in a tire. Given the competitive tire market and the continued need to lower the cost of manufacturing tires, there exists a desire to decrease the cost of innerliners while maintaining their performance.